Non-portable arm exercise machines are disclosed in U.S. Pat. No. 2,668,709 of Boyko for a chair mounted arm exerciser, U.S. Pat. No. 4,060,241 of Hegel for a wall mounted arm exerciser, U.S. Pat. No. 3,309,084 of Simmons, also for a wall mounted arm exerciser and U.S. Pat. No. 5,580,338 of Scelta. Scelta '338 discloses a non-walking lap supported arm bike exerciser.
Portable body worn arm exercisers are disclosed in U.S. Pat. No. 5,141,223 of Block for a limb exercise harness with elastic band/cords, U.S. Pat. No. 5,328,432 of Gvoich for a belt worn arm stretch exerciser with elastic band/cords, U.S. Pat. No. 1,402,179 of Piscitelli for an arm exercise harness with elastic band/cords, U.S. Pat. No. 1,432,013 of Blake for an arm exerciser with elastic band/cords, U.S. Pat. No. 1,618,273 of Davidson for a belt and harness worn arm exerciser with elastic band/cords, U.S. Pat. No. 2,097,376 of Marshman for an exercise harness with elastic band/cords, U.S. Pat. No. 4,961,573 of Wehrell for a boxing exercise harness with elastic band/cords, and U.S. Pat. No. 5,176,377 of Wilkinson for a limb exercise harness with elastic or non-elastic band/cords.
However the elastic arm exercises with harnesses and elastic bands/cords may be dangerous if the elastic pull cords slip out of the user's hands and fly toward someone else (or the user). Also, rotatable pedals may be better exercise for the shoulders and neck, which might get strained from too much elastic pull, since the force exerted by elastic band/cords gets harder as it stretches, but the force is constant during pedaling.
U.S. Pat. No. 4,986,537 of D'Orta describes a hip-worn sidewinder exerciser with rotational crank handles which are turned by the arms at the side of the wearer. However, D'Orta does not allow the wearer to exercise the arms in front of the wearer.
U.S. Pat. No. 5,234,395 of Miller and U.S. Pat. No. 5,916,070 of Donohue both disclose arm exercisers each with an inelastic cord which is alternately pulled forward by the left and right arms in a reciprocating matter. U.S. Pat. No. 6,659,921 of Vernon describes an arm exercise harness with a resilient, stretchable or elastic cord set which is pulled by the arms of the wearer.
It is known to simulate physical activity on an exercise machine by increasing or decreasing resistance. Resistance is a “torque” quantity in units of “length times force” such as inch-pounds or foot-pounds. Watts is a power term like horsepower: power=torque times rotational speed. One relationship is torque in inch pounds=(HORSEPOWER×63,025)/RPM. Another relation is 1 Watt=44.2537 foot-pounds/minute. A kilogram calorie (physiological type) is a unit of heat or energy akin to a Watt-second. For example, 1 kg calorie=1.162 watt-hours and is derived by integrating Watts over time.
To calibrate or manipulate “resistance” in terms of Watts, one must know both the torque and the speed simultaneously. So a unit that sets “resistance” to expend energy at a certain rate of power in Watts, one determines a measure of the torque and a measure of rotational speed (such as RPM) which is usually derived from a speed sensor such as a digital encoder (or a conventional tachometer).
U.S. Pat. No. 7,727,125 of Day describes a foot pedal exercise device with a servo controller controlling brake resistance to simulate harder exercise. The method used in Day '125 or similar stationary powered exercise gym machine in a gym or rehab venue with utility supplied electric power may not be feasible for a portable walk-around unit because of power limitations. For example, if a brake drum and pad are forced together directly by an electromagnetic linear actuator, it would be too power-hungry. However, a motor and lead screw works well just using a small battery for a portable unit.